Telephone-exchange system.



H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED 050.29. I9I6.

1,27 9,841 Patented Sept. 24, 1918.

llargliml 556 #4 WW My:

Henry I? C/ausam.

UNITED STATES PATENT OFFICE.

HENRY P. CLAUSEN, OF MOUNT VERNON, NEW YORK, ASSIGNOR TO WESTERN ELEC-TRIO COMPANY, INCORPORATED, 031' NEW YORK, N. Y., A CORPORATION OF NEWYORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented. Sept. 2. 1918.

Application filed December 29, 1916. Serial No. 139,564.

phone-Exchange Systems, of which the folwholly or in part.

In systems in which the release of a train of switches used in settingup aconnectlon is controlled wholly by the calllng subscriber, anundesirable condition will arise if.

the calling subscriber is the first to replace his receiver. In thiscase the entire train of switches would be released, but, due-to thefact that the called subscriber still has his receiver off the hook, hisline relay would become energized and operate a line switch to seize afirst selector. To obviate this difficulty, systems in which the releaseof the connector switches is controlled jointly by the calling andcalled subscribers have been devised. However, in systems of the lastmentioned type, if the calling subscriber accidentally disconnects byoperating his.

switchhook and thus releases the switches, with the exception of theconnector, it would be impossible for him to again establish aconnection to the called subscriber unless in the meantime the calledsubscriber replaced his receiver and thereby released the connector.

It is the object of the present invention to provide means whereby acalling subscrilier, having accidentally broken down the connection, mayobtain connection to the called party through another connector switch,means being necessarily present to prevent the called line from testingbusy.

It is an additional object of the invention to render the connectorswitch inaccessible to other selectors while awaiting thereestablishment of the connection.

A further object of the invention is to provide means whereby the firstconnector will be released as soon as the connection is reestablished.

A feature. of the invention is the use of a relay which is normallyshunted out, but

which, upon disconnection by the calling subscriber, is allowed toenergize. This relay when operated serves to replace ground on theterminal overwhic'h ground was supplied to the release trunk. This relaywill deenergize when connection is reestablished, since it is shuntedby'a direct ground at the connector switch which was used whenreestablishing the connection. Upon its de- "energization' in this case,the relay completes a circuit to allow the release of the connectorswitch with which it is associated.

It is thought the invention will best be understood from the Followingdetailed description, reference being'had to the accompanying drawing.

In the drawing is shown a connector circuit embodying the'features ofthe present invention.

The switches used in the present disclosure are of the step-by-step,up-and-around type, substantially similar in structure to thosedisclosed in Patent No. 815,17 6. Any desired form of switch may,however, be used, since the invention is applicable to a variety ofsystems employing various types of switches.

It has been assumed that the calling subscribers line is arranged to beextended to the connector by means of a line finder, the brushes ofwhich are indicated at 1, 5 and 31, and a first selector. brushes ofwhich are indicated at 6, 7 and 8.

The subscriber at sub-station 1 desiring a connection with a subscriberat sub-station 2, removes his receiver from the hook, whereupon hls llneWlll be extended to a selector by means of the line finder whose brushesare shown at 4, 5 and 31, and which operates in the well-known manner.The first selector is then operated in response to the first set ofimpulses sent out by the calling subscriber by means of an impulse dial3, and operates in a well-known manner to extend the calling line to theconnector shown in the drawing.

As soon as the calling line has been extended to the connector, relay 9is energized over a circuit from grounded battery, left-- hand windingof relay -9, .outer left-band armature and back contact of relay.10, the

substation loop of the calling subscribers line. inncr left-bandarmature and backcontact of relay 10. and the right-hand winding ofrelay 9 to ground. Relay 9 upon energization completes a circuit fromgrounded battery, winding of slow release relay 11, front contact andleft-hand armature of relay 9 to ground.

The subscriber now operates his impulse transmitter to send the secondseries of im pulses. The first interruption of the line circuit causesthe deenergization of relay 9, and completes a circuit from groundedbattery, side-switch wiper 12 and its first contact, winding of primarystepping magnet 13, slow release relay 14, outer left-hand armature andfront contact of relay 11, lefthand armature and back contact of relay 9to ground. Slow release relay 14 is energized in this circuit, andcompletes a-circuit from grounded battery, winding of escape magnet 15,armature and front contact of slow release relay 14 to ground. Relays l1and 14 being slow to release, remain energized during the sending ofthis series of.

impulses. Relay 11 at its inner'left-hand armature and front contactmaintains ground on the release trunk over selector brush 8 and finderbrush 31 to prevent the release of these switches.

Stepping magnet 13 is alternately energized and deenergized, in responseto the impulses, to move the brush shaft a desired number of steps in aprimary direction. Upon the termination of impulses relay ,9 remainsenergized for a comparatively long time, and slow release relay 14 isdeenergized and opens the circuit of escape magnet 15, which deenergizesand releases the side switch into its second position.

\Vhen the final series of impulses is sent, the first denergization ofrelay 9 completes a circuit from grounded battery, side-switch wiper 12and its second contact, winding of secondary stepping magnet 16,left-hand armature and back contact of busy relay 17, winding of slowrelease relay 14, outer lefthand armature and front contact of relay 11,and the left-hand armature and back contact of relay 9 to ground. Relay14 completes a circuit for escape magnet 15 as before, and remainsenergized during the send ing of impulses, while stepping magnet 16advances the brush shaft in a secondary direction. in response to theinterruptions in the line circuit.

At the conclusion of the final series of impulses slow release relay 14is again dcenergized, and provides a test circuit for the escape magnet.This circuit extends from grounded battery, winding of escape magnet 15,armature and back contact of relay 14, winding of busy relay 17,righthand armature and back contact of relay 17, side-switch wiper 18and its second contact, to test brush 19.

If we assume that busy lines are characterized by the presence of directground on their multiple test terminals, and that idle lines arecharacterized by battery potential on their multiple test terminals, themarginal escape ma net 15 will be deenergized if the called line is idleand will release the side-switch wipers into their third positions. y

In the third position of the sideswitch, a

circuit will be completed for relay 20 from A ground is also supplied totest brush 19 from ground at the contacts of relay 11, throughside-switch wiper 18 and its third contact, to render the test terminalsof the called line busy to other calling lines.

Relay 20 at its armatures connects the line conductors to the connectorbrushes 22 and 23.

A circuit is now completed for ringing relay 24 from grounded battery,side-switch Wiper 12 and its third contact, right-hand armature and backcontact of ringing cutoff relay 25, winding of ringing relay24,interrupter 26 to ground. When the brushes of the interrupter 26 areon conducting segments, the relay 24 will be energized and completes aringing circuit to the called substation. This circuit extends from asource of alternating current indicated at 27, upper armatures and frontcontact of relays 24 and 20, brush 22 and its associated contact, theloop of the called subscribers line including the substation bells,connector brush 23 and its associated contact,'lower armatures and frontcontacts of relays 20 and 24 to ground.- The intermittent operation ofrelay 24 results in the projection of ringing current over the line atdesired time intervals.

WVhen the called subscriber answers and removes his receiver from thehook, an energizing circuit for relay 10 will be completed as soon asrelay'24 is in a deenergized condition. This circuit extends fromgrounded battery, right-hand winding of relay 10, upper armature andback contact of relay 20, connector brush 22 and its associated contact,loop of the called subscribers line, connector brush 23 and itsassociated contact, lower armature and front contact of relay 20, lowerarmature and back contact of relay 24, and-the left-hand winding ofrelay 10 to ground.

The energization of relay 10 causes a reversal of the direction ofcurrent flow in the called subscribers line to operate a polar- Thiscurrent reversal is accomplished through left-hand armatures and frontcontacts of relay 10, without allowing relay 9 to de'nergize. 5

A circult for ringing cut-off relay is also I completed from groundedbattery, winding its inner left-hand armature and front con tact. At itsright-hand armature it permanently opens the circuit of ringing relay 21, and prevents the reoperation of this relay. The connection is nowcomplete and the subscribers may converse.

At the termination of the conversation both parties replace theirreceivers, the replacing of the calling subscribers receiver resultingin the deenergization of relayll. Relay 11 at its inner left-handarmature and front contact removes ground from the release trunk, which"results'in the release of the selector and finder in the well-knownmanner. The replacing of the called subscribers receiver results in thedenergization of relay 10. A circuit is then completed from groundedbattery, winding of release magnet 30, off-normal contact 29, outerright-hand armature and back contact of relay 11, inner right-handarmature and back contact of relay 10 to ground. The release magnetcauses the restoration of the switch, and remains energized until thiscircuit is broken by the opening of the off-normal contact 29 when thebrushes are fully restored. The return of the brush shaft at the sametime restores the side-switch wipers to their normal position in theusual manner.

Referring now to the point in the operation just after the second seriesof impulses has been sent, it will be assumed that the desired line' isbusy. In that case direct ground will be connected to test terminal 32,through side-switch wiper 18 of some other connector in its thirdposition; The marginal escape magnet 15 will now remain energized, andsince relay 17 is included in its circuit, relay 17 will also beenergized,.causing the application of busy tone to the calling line.Alternating current is applied to relay 10 over a path from groundedbattery, coil 34,

outer right-hand armature and front contact of relay 17, left-handwinding of relay 10 to ground. The inductive action of this current onthe windings of relay 10 causes a tone to be transmitted over thecalling subscribers line through condensers 35 and 36. The callingsubscriber then replaces his receiver and causes the release of theconnector by means of circuits previously described.

Should the calling subscriber accidentally disconnect himself bydel'nessi'ng his switchhook, the operation of the system is as 'follows. The opening of thecalling line circuit results in thedeenergization of relay 9, causing in turn the deenergization of relay11. Relay 11 upon deie'nergization removes ground at its inner left-handarmature from the holding trunk and allows the finder and selector torelease. The release circuit for the connector will not, however, becompleted at this time, since relay 10 is still energized, it beingassumed that the called subscriber does not replace his receiver. If thecalled subscriber should replace his receiver, the connector will berestored as previously described, but ifhe does not understand the causeof interruption and keeps his receiver from the hook the c'onnector willnot be restored. Upon the deenergization of moved, and thisrrelay isenergized in series with cut-off relay 37, which was energized uponseizure of the called line, to remove the control of the calledsubscribers line relay in the well-known manner. Relay 21 uponenergization completes a circuit from grounded battery, winding of relay38, lefthand armature and front contact of relay 21 to ground. Relay38,'whichis slow to act, re places ground on the test terminal of theconnector switch and thereby'makes this switch test busy to otherhunting selectors. If the connector were notmade busy to other huntingthis case the escape magnet of such other connector will be allowed todeenergize, be-

ing marginal in character, and will, therefore, not energize through theresistance of relay 21, this circuit extending from ground-' 'relay 11the shunt around relay 21 is reed battery, winding 'OfGSCZtPB magnet 15of I such other connector, armature and back contact of relay 14,winding of busy relay 17, inner right-hand armature and back contact ofrelay 17:, side-switch wiper 18 and its second contact, test brush 19 ofsuch other connector, multiple test terminals 32, test brush 19 of theconnector shown in the drawing, side-switch wiper 18 and its thirdcontact, winding of relay 21 to ground.

The de'energization of the escape magnet at the other'connector allowsthe side-switch wipers of such other connector to be released into thethird position, whereupon relay 21 will be shunted by a path to groundat the inner left-hand armature and front contact of relay 11 at suchother connector. A circuit 7 of relay 11, the inner right-hand armatureand front contact of relay 10, right-hand armature and back contact ofrelay 9, inner right-hand armature and back contact of relay 11,right-hand armature and back contact of relay 21 to ground. Theconnector switch shown in the drawing is then released, as previouslydescribed.

The deenergization of relay 21 results in the denergization of relay 38,which then removes ground from the test terminal of the connector shownin the drawing.

It is to be observed that the inner right hand armature of relay 11 mustrequire more time in falling off than the inner left-hand armature ofrelay 11, in order that the shunt around the windings of relay 21 may beremoved for a sufficient length of time in advance of .the closureof theinner right-hand armature of relay 11 on its back-contact to give relay21 sutficient time to energize and prevent the closure of the releasecircuit at its right-hand'armature and back contact. The desired time offalling off of these armatures may be accomplished by suitableadjustment of therelay contacts.

ing

What is claimed is: 1. In a telephone exchange system, calland calledsubscribers lines, automatic switches, means including a train of saidautomatic switches to establish a connection from a calling to :1 calledsubscribers line, means controlled jointly by said calling and calledsubscribers to controlthe release of the final switch of said train,means con trolled by said calling subscriber to control the release ofthe preceding switches of said train, and means including another finalswitch to reestablish connection between said subscribers should thepreceding switches only be released by the calling subscriber. V

2. In a telephone exchange system, calling and called subscribers lines,automatic switches, meansincluding'a train of said automatic switches toestablish connection from a calling to a called subscribers line,

means to control the release of the preceding switches of saidtrain,'means including another final switch to reestablish connectionbetween said subscribers should the preceding switches be released 'bythe calling subscriber, and means to render said first-mentioned finalswitch inaccessible to use by calling subscribers until reconnection hasbeen established.

3. In a telephone exchange system, calling and called subscribers lines,automatic switches, means including a train of said automatic switchesto establish connection from a calling to a called subscribers line,means controlled jointly by said calling and called subscribers tocontrol the release of the final switch of'said train, means controlledby said calling subscriber to control the release of the precedingswitches of said train, means including another final switch toreestablish connection between said subscribers should the precedingswitches be released b the calling subscriber, and means operatesimultaneously with said reconnection to release said first-mentionedfinal switch.

4. In a telephone exchange system, calling and called subscribers lines,automatic switches, means including a train of said automatic switchesto establish connection from a calling to 3. called subscribers line,means controlled jointly by said calling and called subscribers tocontrol the release of the final switchof said train, meanscontrolled'by said calling subscriber to control the release of thepreceding switches of said train, means including another final switchto reestablish connection between said subscribers should the precedingswitches be released by the calling subscriber, means to render saidfirst-mentioned final switch inaccessible to use by calling subscribersuntil reconnection has been established, and means operatedsimultaneously with such reconnection to release said first-mentionedfinal switcln 5. In a telephone exchange system, calling and calledsubscribers lines, connector switches, meansincluding one of saidconnector switches to establish connection from a calling to a calledsubscribers line, means to prevent the establishment of a talkingconnection it the called line is busy, means to establish a talkingconnection if the called line is idle, means controlled by saidconnector switch to make said called line test busy to other connectors,and means made operative under the control of the said callingsubscriber to render said busy test ineffective.

6. In a telephone exchange system, calling and called subscribers lines,connector switches, means including one of said connector switches toestablish connection from a calling to a called subscribers line, meansto prevent the establishment of a talking connection it the called lineis busy, means for establishing a talking connection if the called lineis idle, means to render said busy test ineffective under certainconditions, a relay, a release circuitpartially controlled at contactsof said relay, and means made operative under the control of the callingsubscriber toafl'ect the condition of said relay.

7. In av telephone exchange system, calling and called subscriberslines, automatic switches, means including a train of said automaticswitches to establish connection from a calling to a called subscribersline, testing means at the final switch of said train to prevent theestablishment of a talking connection it the called line is busy, meansto establish a talking connection it the called line is idle, meanscontrolled by said final switch to make said called line test busy toother final switches, means Controlled jointly by said calling and saidcalled subscribers to ontrol the release of the final switch of saidtrain, moms controlled by said calling subscriber to control. therelease of the precedingswitches of said train, a relay, means includingcircuits controlled at contacts of said relay to render said firstmentioned final switch inaccessible to use by calling subscribers untilreconnection has been established and to operate simultaneously withsuch reconnect-ion to release said first mentioned final switch. andmeans made operancctcd pair of calling and called lines, and

means under control of said calling'line, party to said connected pazrof lmes; for

removing said excluding means from said.

called line.

In witness whereof, I hereunto subscribemy name this 28th day ofDecember, A. D., 1916.

HENRY P. GLAUSEN.

